Monday, April 3, 2017

Cannabis is bad for athletes,... well, unless they're asthmatics; and in that case they'd better use beta-agonists, which have welcome previously discussed ergogenic "side effects".

It's April and time for another installment of the SuppVersity Short News about sports medicine and related topics. In articles like the one at hand, I discuss a selection of recent studies - usually from a single journal like, in this case, the Journal of Science and Medicine in Sport and often, as in this case, based on papers that have been accepted for publication, already but haven't been published, yet.

In today's installment we'll deal with cannabis, shoe cushings and the brain building (BDNF boosting effects) of hypertrophy-oriented resistance training... and, not to forget, the fallacy of taking into account only exercise-induced stressors, when you periodize your training.

Read about more or less exercise-related studies at the SuppVersity

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Cannabis, how bad is it for athletes? (Kennedy 2017) -- While most serious athletes would probably never even think about smoking dope, many wanna-be fitness athletes don't want to or can no longer stay away from cannabis. For this group of people, in which some even claim their physical performance would benefit from THC abuse, it is quite unfortunate that there are only 15 published studies have investigated the effects of THC in association with exercise protocols.

Unsurprisingly, none of the studies showed any improvement in aerobic performance. What is intriguing, though, is that exercise-induced asthma was shown to be inhibited in one and the marihuana precipitated angina lead to at a lower workload (100% of subjects) and probably reduced strength in all studies.

Moreover, the review by Kennedy highlights that some subjects could not complete an exercise protocol because of adverse reactions (e.g. palpitations, or sudden weakness) to cannabis. Rather than to take cannabis, athletes who have become addicted to cannabis should and could use exercise to reduce their cannabis cravings; after all, Baily et al. (2012) were able to show that cannabis cravings decrease sign. with moderate exercise.

Shoe cushioning injury-protective only during unexpected movements (Fu 2017) -- Even though the sneaker industry tries to generate the opposite impression, to date, few rigorous scientific studies have been conducted to understand the impact mechanics and muscle activation characteristics of different landing tasks and the influence of shoe properties.

In a recent study, scientists from the Shanghai University of Sport tried to add to this evidence by examining the effects of shoe cushioning on impact biomechanics and muscular responses during drop landings.

As already hinted at in the bolded lead to this bullet-point, the beneficial effects of an extra cushioning were observed in the male collegiate basketball players, who performed bipedal landings from self-initiated and unexpected drops (SIDL and UDL) from a 60-cm height wearing highly cushioned basketball shoes (Bball) and less cushioned control shoes (CC) in the study at hand, were observed only in the unexpected condition.

More specifically, both peak vertical ground reaction forces (GRF) and heel acceleration were significantly lower in Bball compared to CC. Furthermore, the EMGRMS of TA, RF, VL, and BF muscles showed a significant decrease in Bball compared to CC within the 50 ms after contact.

Hypertrophy training ain't making you dumb, but smart (Marston 2017) -- Previously, the release of brain-derived neurotrophic factor (BDNF | promotes the survival of nerve cells (neurons) by playing a role in the growth, maturation (differentiation), and maintenance of these cells) has been shown to increase in an intensity-dependent manner in response to aerobic exercise. In the absence of evidence from resistance training studies, however, you would often read that this increase in the "brain building hormone" was exclusive to aerobic training. That this is by no means the case has just been shown in a recent study in eleven untrained to intermediately trained males (age: 25.0 ± 1.3 yr) and five untrained females (age: 23.2 ± 1.1 yr).

All subjects undertook the same two bouts of resistance exercise: strength (five sets of five repetitions, 180 s recovery) and hypertrophy (three sets of ten repetitions, 60 s recovery), both implemented to fatigue to examine the effect on serum BDNF and blood lactate levels immediately post-, and 30 min post-exercise.

As you can see in Figure 2, there was a clear interaction (p < 0.01; ES = 0.52) with BDNF for both types of exercise, but the hypertrophy regimen resulted in significantly greater BDNF levels when compared with strength exercise.

The fact that the levels declined non-significantly after 30 minutes should not scare you, by the way, similar effects have been observed for the allegedly healthier "cardio" (=aerobic) training in the past, as well.

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That's it? Not exactly... In a recent paper Buckner et al. (2017) point out that the often-heard application of Hans Selye's "General Adaptation Syndrome" theory to resistance training is at least highly questionable. While the original application of GAS to resistance exercise was to avoid overtraining, trainers and trainees extend its validity to another domain when they use it as the guiding principle in their periodized training programs: As Buckner et al point out, "periodization has [yet] become the gold standard of programming, taking on an identity outside its original purpose of managing 'adaptation energy' and avoiding overtraining", which does not take into account stress from everyday life and stress from supplemental exercise.

"This is important", as the authors point out, because "periodized resistance training should be training that attempts to account for the totality of stress in an individual’s life" (my emphasis in Buckner 2017) - and that's valid for pro-athletes and, even more so, hobby athletes like you and me who have a regular full-time job and a private life that's not always stress-free, either | Comment!

Buckner, et al. "The General Adaptation Syndrome: Potential misapplications to resistance exercise." Journal of Science and Medicine in Sport. Available online 21 March 2017.

Fu, et al. "Shoe Cushioning Reduces Impact and Muscle Activation during Landings from Unexpected, but not Self-initiated, Drops." Journal of Science and Medicine in Sport. Available online 21 March 2017.

Kennedy, et al. "Cannabis: exercise performance and sport. A systematic review." Journal of Science and Medicine in Sport. Available online 21 March 2017.

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